Why GPS tracks contain errors
Consumer GPS receivers may experience positioning errors caused by satellite geometry, buildings, dense forests, rock walls or signal reflections.
Even when the user is stationary, the GPS may record small position oscillations that produce noisy tracks and artificially increased distances.
Cleaning anomalous points
Cleaning a GPX track consists of identifying and removing incorrect or inconsistent points compared to the real route.
Anomalous points may show sudden jumps, unrealistic speeds or evident deviations from the track direction.
Correcting elevation data
Elevations recorded by GPS are often less accurate than horizontal coordinates. To improve the elevation profile it is possible to use DEM models (Digital Elevation Model).
Replacing GPS elevations with DEM data makes it possible to obtain more stable elevation charts and more accurate elevation gain analyses.
Reducing GPS noise
Track filtering makes it possible to reduce random GPS position oscillations.
This operation improves track readability, reduces artificial zig-zags and makes distance and speed more realistic.
Using OkMap to correct tracks
OkMap allows manual editing of track points, correction of elevation data and comparison of the track with raster maps or topographic cartography.
The editing tools also allow removal of incorrect segments, merging of multiple tracks and improvement of the overall GPX data quality.